The invention relates to a compact filter, in particular, a compact air filter for motor vehicles. The compact filter comprises a compact filter element that is arranged in a filter housing so as to be exchangeable, wherein the compact filter element comprises a filter body having a longitudinal axis.
For filtering air, so-called compact filters are widely used that are in particular comprised of layered filter paper. An undulated filter paper web is applied to a flat filter paper web. The semi-finished product produced in this way is wound to a filter body or stacked so that a plurality of parallel extending gas channels will result. These gas channels are alternately closed off by plugs. Incoming air flows from the raw (unfiltered air) side of the filter into the gas channels that are open at the inlet side and is forced, as a result of the plugs at the outlet side, to pass through the filter walls into the neighboring gas channels. From here, the filtered air flows through the gas channels at the outlet side to the pure (filtered air) side of the filter.
By means of the aforementioned construction air filters of a very compact configuration can be produced. Depending on the available space, the wound body or the stacked body and thus the filter as a whole can be designed to be flat with a narrow side and a long side. Tight mounting spaces can make it necessary to provide an asymmetric inflow in which the inlet opening, particularly in the area of the narrow side, is positioned with angular or positional displacement relative to the longitudinal axis of the filter body. The incoming air carries dust particles or the like that as a result of their inertia are not deflected as desired in a direction parallel to the gas channels. As a result of their inertia the dust particles are carried with increased concentration to the wall area of the filter housing that is opposite the inlet opening. As a result of this, dust loading of the compact filter element results that is minimal near the inlet opening and that increases toward the remote side. This non-uniform dust loading causes individual areas of the filter body to clog prematurely so that the filter performance decreases. The potential service life of the compact filter is not completely exploited.
It is an object of the present invention to develop a compact filter of the aforementioned kind in such a way that the uniformity of dirt loading across the base surface of a filter element is improved.